If you have 0.82R, use it.
R1=1/Ifilament
Some years ago I bought box of 1R Mills MRA12, so I used its instead of 0.82R, which was in the kit.
V7 was capable working at 90% potentiometer value with 1.25A.
R1=1/Ifilament
Some years ago I bought box of 1R Mills MRA12, so I used its instead of 0.82R, which was in the kit.
V7 was capable working at 90% potentiometer value with 1.25A.
Work in progress Vin R. C. 25VDC, same PSU as 26 C-L-CMC-C, PSU needs resistors to lower the Vout to 24VDC or maybe 23VDC because the attached pic is the max. attenuatio can gives the trimmer. First to try the valve I used a 50W 6R8 power resistor.
#26 has 7k6 output impedance at 135V, 5.5mA, -10V.
2x, rather 3x anode load required.
3x:22k if R loaded, 180H if choke loaded.
2x, rather 3x anode load required.
3x:22k if R loaded, 180H if choke loaded.
Oops, I lost the tube type.😵
Depends of the operating point.
8-12k or 64..95H ... but anode current is much larger (for example 25..30mA), so dissipating surface (heatsink) is large.
Size of the choke/transformer (large current+large inductance==larger core, larger current==thicker wire==larger core==larger weight) would be large too....the price would go to the sky.
In the R load case the B+ would be uncomfortably large.
Both of them has negligible PSRR, so regulated supply is needed: cost, cost, cost...
BTW when I tested it -for example- only with 100H choke/OPT as anode load, it was much more worse (higher THD, changed -not so good- FFT spectrum), than with higher impedance load (gyrator/CCS).
p.s.
If you use this tube with R or choke load mode, the output impedance will be practically unusable large (even over 5k).
Depends of the operating point.
8-12k or 64..95H ... but anode current is much larger (for example 25..30mA), so dissipating surface (heatsink) is large.
Size of the choke/transformer (large current+large inductance==larger core, larger current==thicker wire==larger core==larger weight) would be large too....the price would go to the sky.
In the R load case the B+ would be uncomfortably large.
Both of them has negligible PSRR, so regulated supply is needed: cost, cost, cost...
BTW when I tested it -for example- only with 100H choke/OPT as anode load, it was much more worse (higher THD, changed -not so good- FFT spectrum), than with higher impedance load (gyrator/CCS).
p.s.
If you use this tube with R or choke load mode, the output impedance will be practically unusable large (even over 5k).
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What's the goal of using parafeed OPT in preamp?
Here it only means disadvantage: costly capacitor, costly transformer, degrading bandwidth and distortion.
Here it only means disadvantage: costly capacitor, costly transformer, degrading bandwidth and distortion.
"CCS loading of output stage"
Apples and oranges....
It's totally meaningless in case of 801a (mu=8) as preamp.
You should decide what you want.
Apples and oranges....
It's totally meaningless in case of 801a (mu=8) as preamp.
You should decide what you want.
I'm sorry Bela you are right, low mu + OPT left the lineamp with a little gain, no gain or negative gain.🙏
